Brushless dc motor with bearings

ABSTRACT

A PAP device for generating a supply of pressurized gas to be provided to a patient for treatment includes a housing, a core including a motor and at least one impeller, and a vibration isolation system to support the core within the housing in a flexible, vibration-isolated manner.

CROSS-REFERENCE TO APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos.60/853,778, filed Oct. 24, 2006, and 60/929,558, filed Jul. 3, 2007,each of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to electric motors, and more particularlyto bearing supported rotors of the electric motor. The present inventionalso relates to electric motors for positive airway pressure (PAP)devices or flow generators used for treatment, e.g., of Sleep DisorderedBreathing (SDB) with Non-Invasive Positive Pressure Ventilation (NIPPV).

BACKGROUND OF THE INVENTION

Bearings are usually employed in pairs and in coaxial arrangements tosupport a rotating member, e.g., motor shaft. Ideally, the two bearingsare located by a stationary member that constrains the two bearings inperfect axial alignment. Real world designs are less than perfect and,therefore, compromise bearing performance.

A widely employed bearing suspension mode involves holding each bearingwithin a separate housing structure and fitting those housing structurestogether to approximate a coaxial bearing arrangement. For example, FIG.7 illustrates a housing H holding bearing B1 and a cap C holding bearingB2, the cap C being fitted to the housing H to support a rotor R betweenthe bearings B1, B2.

There are two main classes of constraints on the packaging of bearings.One constraint relates to the practical limits of manufacturingprecision, and another constraint relates to the need to attach andefficiently package items that must rotate.

With respect to the first constraint, although the precision of partforming technologies improves continuously, the state of the art is farfrom perfect. Furthermore, increased precision usually translates togreater expense, often dissuading a manufacturer from embracing thestate of the art processes.

The second constraint is driven by the need to place items (such as arotor/stator) between bearing pairs. This leads to the use of a two parthousing construction. A consequence of multipart housings is that theyaccumulate unwanted tolerance build-up at each faying or joint surface.

A less widely employed bearing suspension mode is to utilize a singlemetallic tube to house the bearing pair, and to hang the rotor from oneend in cantilever fashion, i.e., an outer rotor design. For example,FIG. 8 illustrates a metallic tube T housing bearings B1, B2, and arotor R supported by the bearings B1, B2 in cantilever fashion tosupport an impeller I. However, the metallic tube prevents a high speedmagnetic rotor from being packaged between the bearings, i.e., aninternal rotor design, because magnetic fields cannot effectively crossa metallic barrier without significant loss of flux density and/orincreased heat. Also, there are practical limits to how much mass andlength can be cantilevered from a set of high speed bearings. Therefore,such designs tend to be axially short in length.

Thus, a need has developed in the art for an improved arrangement thatdoes not suffer from the above-mentioned drawbacks.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a rotor supporting structure tosupport a rotor in use.

Another aspect of the invention relates to a bearing arrangement havingat least two bearing portions supported on a common member, e.g.,bearing tube.

Another aspect of the invention relates to a brushless DC motor withbearings retained in a stationary tube having at least a portion that issufficiently magnetically transparent to allow a magnetic field to passthrough it, e.g., non-electrically conductive and/or non-magnetic tube.In the context of an embodiment of the invention, a non-conductivematerial may be a material with relatively high resistivity (forexample, in the vicinity of 2 micro Ohm-m or more) and a non-magneticmaterial may be a material with relatively low magnetic permeability(for example, in the vicinity of 2 or less). The acceptable ranges ofthese material characteristics may vary from case to case. The tube maybe generally thermally conductive, and such tube can be metallic and/ornon-metallic or semi-metallic.

Another aspect of the invention relates to a brushless DC motorincluding a rotor, a magnet provided to the rotor, a pair of bearings torotatably support the rotor, a stator assembly that at least partlysurrounds the rotor and magnet thereof, and a bearing tube having anexterior surface and an interior surface that defines a tube interior.The stator assembly is adapted to control movement of the rotor. Thestator assembly is provided along the exterior surface of the tube andthe bearings are provided along the interior surface of the tube tosupport the rotor and magnet within the tube interior. The tube has atleast a portion that is sufficiently magnetically transparent to allow amagnetic field to pass between the magnet and the stator assembly.

Another aspect of the invention relates to a brushless DC motorincluding a rotor having a magnet, a stator assembly adapted to controlmovement of the rotor, and a tube provided between the rotor and thestator assembly. The tube has at least a portion that is sufficientlymagnetically transparent to allow a magnetic field to pass between themagnet and the stator assembly.

Another aspect of the invention relates to a brushless DC motorincluding a magnetic rotor rotatably supported between a pair ofbearings, a stator assembly surrounding the rotor and adapted to controlmovement of the rotor, and a tube to retain the bearings and rotorwithin an interior of the tube. The tube has at least a portion that issufficiently magnetically transparent to allow a magnetic field to passbetween the magnetic rotor and the stator assembly.

Another aspect of the invention relates to a PAP device for generating asupply of pressurized gas to be provided to a patient for treatment. ThePAP device includes a housing, a core including a motor and at least oneimpeller, and a vibration isolation system to support the core withinthe housing in a flexible, vibration-isolated manner.

Another aspect of the invention relates to a PAP device for generating asupply of pressurized gas to be provided to a patient for treatment. ThePAP device includes a housing, a core including a motor and at least oneimpeller, and a vibration isolation system to support the core withinthe housing in a flexible, vibration-isolated manner. The vibrationisolation system is adapted to be coupled to windings of a statorassembly to conduct current from an external source to the windings.

Another aspect of the invention relates to a brushless DC motorincluding a rotor, a stator assembly surrounding the rotor and adaptedto control movement of the rotor, a support structure to support therotor and the stator assembly in an operative position, and a vibrationisolation system provided to the support structure and adapted tosupport the support structure within a housing in a flexible,vibration-isolated manner.

Another aspect of the invention relates to a method for manufacturing amotor. The method includes forming a tube having at least a portion thatis sufficiently magnetically transparent to allow a magnetic field topass through it, providing a magnetic rotor to an interior portion ofthe tube, and providing a stator assembly to an exterior portion of thetube to control movement of the magnetic rotor.

Another aspect of the invention relates to a rotor supporting structureincluding at least one bearing support portion adapted to support abearing and a sufficiently magnetically transparent portion to allow amagnetic field to pass through it.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 is a partial cross-sectional view of an electric motor includinga bearing tube according to an embodiment of the present invention;

FIG. 2 is a schematic view of a PAP device including an electric motoraccording to an embodiment of the present invention;

FIG. 3-1 is a perspective view of a rotor, tube, and stator assembly foran electric motor according to another embodiment of the presentinvention;

FIG. 3-2 is a cross-sectional view of the assembly of the electric motorshown in FIG. 3-1;

FIG. 4-1 is a perspective, cross-sectional view of a PAP deviceaccording to another embodiment of the present invention;

FIG. 4-2 is a top view of the PAP device shown in FIG. 4-1;

FIG. 4-3 is another cross-sectional view of the PAP device shown in FIG.4-1;

FIG. 5-1 is a perspective, cross-sectional view of a PAP deviceaccording to another embodiment of the present invention;

FIG. 5-2 is another cross-sectional view of the PAP device shown in FIG.5-1;

FIG. 5-3 is an enlarged cross-sectional view of a portion of the PAPdevice shown in FIG. 5-1;

FIG. 5-4 is a side view of the PAP device shown in FIG. 5-1;

FIG. 5-5 is a perspective view of a core of the PAP device shown in FIG.5-1;

FIG. 5-6 is a cross-sectional view of the core shown in FIG. 5-5;

FIG. 6 is a cross-section view illustrating a method for assemblingbearings according to an embodiment of the present invention;

FIG. 7 is a schematic view of a prior art bearing suspension mode; and

FIG. 8 is a cross-sectional view of another prior art bearing suspensionmode.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodimentswhich may share common characteristics and features. It is to beunderstood that one or more features of any one embodiment may becombinable with one or more features of the other embodiments. Inaddition, any single feature or combination of features in any of theembodiments may constitute additional embodiments.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that the PAPdevices described herein may be designed to pump fluids or gases otherthan air.

1. Electric Motor

FIG. 1 illustrates an electric motor or tube motor 10 according to anembodiment of the present invention. In the illustrated embodiment, themotor 10 is in the form of a brushless DC motor. The motor 10 includesan optional housing 12, a rotatable shaft or rotor 14, a permanentmagnet 16 mounted on the rotor 14, and a stator assembly 18 thatsurrounds the rotor 14 and magnet 16 thereof. The rotor 14 is rotatablysupported by a pair of bearings 20 that are retained or housed by abearing tube 22. The bearings 20 may be any suitable type as known inthe art, e.g., conventional rolling element bearings, fluid bearings(air or liquid), sleeve bearings, or other type.

The optional housing 12 encloses the stator assembly 18, rotor 14,magnet 16, bearings 20, and bearing tube 22. An end cap 24 is providedto the housing 12 to allow access to the housing interior and thecomponents enclosed therein. In addition, the end cap 24 and end wall 26of the housing each include an opening 28 to allow respective endportions 30, 32 of the rotor 14 to extend therethrough. Each end portion30, 32 is adapted to be coupled to a device, e.g., impeller, to causespinning movement of the device. However, the motor 10 may be structuredsuch that only one end portion of the rotor 14 extends from the housing12. In use, an electronic controller (typically provided as part of PAPdevices or flow generators available from ResMed) controls operation ofthe stator assembly 18 to control spinning movement of the rotor 14 andhence the device, e.g., impeller.

1.1 Bearing Tube

In the illustrated embodiment, the bearing tube 22 comprises arelatively thin-walled, stationary, stable tube.

1.1.1 Properties

The bearing tube 22 has at least a portion that is sufficientlymagnetically transparent to allow a magnetic field to pass through it.In an embodiment, such “magnetic transparency” may be provided by one ormore the tube's material properties, e.g., non-electrically conductive,magnetically transparent or non-magnetic, and/or thermally conductivetube. Alternatively, such “magnetic transparency” may be provided by oneor more perforations in the tube as described in greater detail below.

In some applications, it may not be necessary for the tube to have allthe material properties described above (non-electrically conductive,magnetically transparent, and thermally conductive) as the tube maysimply include one or more of these properties and/or a sufficientdegree of these properties (e.g., partially electrically conductiveand/or partially heat conductive). In addition, non-conductive refers tothe (non)conduction of electricity, although the tube 22 may be heatconductive in embodiments, which may be beneficial for warming the airand/or cooling the blower elements. The tube includes adequate “magnetictransparency”, “non-electrical conductivity”, and/or “thermalconductivity” to allow sufficient magnetic flux near the magnet withoutoverheating.

In the context of an embodiment of the invention, a non-conductivematerial is understood to be a material with relatively high resistivity(for example, in the vicinity of 2 micro Ohm-m or more) and anon-magnetic material is understood to be a material with relatively lowmagnetic permeability (for example, in the vicinity of 2 or less). Theacceptable ranges of these material characteristics may vary, e.g.,depending on application.

The tube may be thermally conductive to allow heat release (heat maycreate drag on motor, inefficient power, reduced life on bearings, tubedistortion, etc.).

In addition, the tube may have different material properties along itslength or circumference, e.g., different levels or regions of “magnetictransparency”, “non-electrical conductivity”, and/or “thermalconductivity.” That is, portions of the tube may have one or more ofthese properties, but other portions of the tube may not.

Magnetic transparency should be greater in the vicinity of the magnetand stator assembly, where flux densities may be expected to be higher.Outside of that region, different properties could be tolerated and insome cases may not be necessary. For example, it could be advantageousto construct the tube from different elements that are fastenedtogether, wherein some of the elements are magnetically transparent, inlocations where that is desirable, and other elements of the tube aremore thermally conductive, for example.

1.1.2 Materials

The bearing tube 22 may be constructed of non-metallic materials, e.g.,ceramics (e.g., stabilized zirconia), glass, polymers, filled (butnon-conductive) polymers, or reinforced polymers (e.g., Fiberglass,Carbon, Boron, etc.). However, the tube can also be metallic orsemi-metallic. In an embodiment, the tube may include differentmaterials along its length or circumference.

1.1.3 Shapes

In the illustrated embodiment, the tube has a circular cross-sectionalconfiguration along its length. However, it should be appreciated thatthe tube may have other suitable shapes, e.g., circular or round,square, polygonal, conical, etc.

Also, the tube may include one or more parts (e.g., multi-partconstruction), e.g., different elements with different properties thatare fastened together.

In an embodiment, the tube may be sufficiently perforated (e.g., one ormore holes, openings, and/or slits) to allow a magnetic field to passthrough it. In such embodiment, the tube may or may not includenon-electrically conductive, magnetically transparent, and/or thermallyconductive material properties.

1.1.4 Combinations

It is to be understood that any single feature or combination offeatures described above may constitute embodiments of the tube. Thatis, the tube may include any suitable combination of properties,materials, and/or shapes as described above.

1.1.5 Portions

Also, it should be understood that portions of the tube may have one ormore of the features described above, but other portions of the tube maynot.

1.1.6 Bearing Support

As illustrated, the stator assembly 18 is provided to a center portion40 of the tube 22 along an exterior surface 42 thereof. The bearings 20are provided to respective end portions 44, 46 of the tube 22 along aninterior surface 48 thereof. The tube 22 retains the bearings 20 insubstantially perfect axial alignment. The bearings 20 support the rotor14 and magnet 16 within the tube interior. In addition, the magnet 16 ispositioned between the bearings 20 such that the magnet 16 is alignedwith the stator assembly 18.

The inside diameter of the tube 22 is substantially similar to theoutside diameter of the bearings 20. This allows the bearings 20 to besecurely and stably retained within the tube 22, e.g., by friction fit,adhesive, etc.

The tube 22 is sufficiently “magnetically transparent” (e.g.,non-magnetic, non-electrically conductive, and/or thermally conductive),which allows the motor 10 to have a design in which the magnetic rotor14 is located between the bearings 20 within the tube 22, as illustratedin FIG. 1. That is, the stator assembly 18 can act on the magnetic rotor14 positioned within the tube 22 without significant loss of fluxdensity and/or increased heat, if any. Thus, the tube 22 provides stablephysical properties and is adequate to support the needs of the motorapplication. It is noted that the bearing tube 22 may be incorporatedinto other motor arrangements or other applications where “magnetictransparency” may be beneficial.

1.2 Advantages

The motor arrangement of FIG. 1, in which the magnetic rotor 14 ispositioned within the “magnetically transparent” tube, 22 has severaladvantages. For example, the motor arrangement provides superiorbearing-to-bearing alignment. The superior alignment results in improvednoise and/or improved life. In addition, the superior alignment resultsin the ability to better accommodate fluid bearings, e.g., when thematerials of the rotor and the tube have closely matched thermalexpansion coefficients (e.g., both the tube and rotor may be made ofstabilized zirconia).

The motor arrangement also provides superior compactness (e.g., therotor may reside between the tube mounted bearings, not cantilevered),superior dynamic response due to an inherently low inertia rotor, andsuperior rigidity due to simplicity of construction. In addition, themotor arrangement provides superior accommodation of both fluid bearingsand a double-ended, impeller blower construction (e.g., when the motoris incorporated into a PAP device or flow generator as described below).

Further, when rolling element bearings are used, matched thermalcoefficients of the tube and rotor may allow one to eliminate a preloadspring. Specifically, one method for assembling bearings includes usinga preload spring that applies a force to the bearings to ensure theyremain correctly aligned and retained in position against the ends oftube, e.g., against flange 380 for the lower bearing and against taperedflange 382 for the upper bearing as shown FIG. 4-3. As an alternative tosuch method, the preload spring may be eliminated and the bearings maybe retained in position by an adhesive, e.g., glue, or other suitablefixing means, e.g., mechanical fasteners, etc. The bearings may be of arange of varieties. For example, the bearings could be constructed assleeve types, duplex types, magnetic types, etc.

Such an alternative method is illustrated in FIG. 6. In such method, aforce may be applied (e.g., by spring 536 as indicated in dashed lines)to force the bearings 520, 525 against respective flanges 582, 580 andin correct alignment. Once aligned, an adhesive A, e.g., glue, or otherfixing means may be applied between the bearings 520, 525 and the tube522 to fix and retain the bearings 520, 525 in position while the forceis being applied, e.g., by the spring 536. Once the bearings 520, 525are fixedly attached, the force may be removed.

A potential problem with this alternative method is that when the motorwarms up, different components (e.g., such as the rotor and the tube)will expand according to their individual thermal expansion coefficientwhich relates to the material used to make the components. Thus, if therotor and the tube materials have two different thermal expansioncoefficients allowing them to expand at different levels, the bearingsmay move or misalign causing an imbalance in the motor. In order toprevent such problems from occurring, the tube and the rotor may be madefrom the same material to have the same thermal expansion coefficient orthe tube and the rotor may be made from two different materials with thesame thermal expansion coefficient.

2.0 Motor Incorporated into PAP Device

The motor 10 may be incorporated into a PAP device or flow generatorstructured to generate a supply of pressurized gas to be provided to apatient for treatment, e.g., of Sleep Disordered Breathing (SDB) withNon-Invasive Positive Pressure Ventilation (NIPPV). In an embodiment,the motor may be constructed to operate up to about 30,000 rpm and/or 8mNm torque.

For example, FIG. 2 is a schematic view of a PAP device or flowgenerator 60 including the motor 10. As illustrated, the PAP device 60includes a housing 62 and a blower 64 supported within the housing 62.The blower 64 is operable to draw a supply of gas into the housing 62through one or more intake openings (not shown, but typically providedat the bottom or side wall of the flow generator housing) and provide apressurized flow of gas at an outlet 66. The supply of pressurized gasis delivered to the patient via an air delivery conduit that includesone end coupled to the outlet 66 of the PAP device 60 and an oppositeend coupled to a mask system that comfortably engages the patient's faceand provides a seal. In an embodiment, the blower is constructed todeliver pressurized gas suitable for CPAP or NIPPV, e.g., in the rangeof 4-28 cmH₂O, at flow rates of up to 180 L/min (measured at the mask),depending on patient requirements. Also, the blower may be configured todeliver bilevel therapy or variable pressure therapy (e.g., low range of2-6 cmH₂O and high range of 6-30 cmH₂O).

The blower 64 is supported by or within the housing 62, and includes atleast one impeller 68 and the motor 10 to drive the at least oneimpeller 68. In the illustrated embodiment, the blower 64 has adouble-ended, impeller blower construction. Specifically, the motor 10includes the arrangement shown in FIG. 1, and each end portion 30, 32 ofthe rotor 14 is coupled to an impeller 68. However, the blower 64 mayinclude a single impeller coupled to the motor 10.

The motor may incorporated into blower assemblies such as thosedisclosed in U.S. Pat. No. 6,910,483, U.S. Patent Publication No.2005/0103339, and U.S. Provisional Patent Applications 60/730,875,entitled “Multiple Stage Blowers and Nested Volutes Thereof” filed Oct.28, 2005, and 60/775,333, entitled “Blower Motor with Flexible SupportSleeve” filed Feb. 22, 2006, each of which is incorporated herein byreference in its entirety.

Also, the motor 10 may be employed in other applications.

2.1 Advantages

A PAP device or flow generator 60 including the motor arrangement ofFIG. 1 has several advantages. For example, the motor arrangement ofFIG. 1 provides a quieter, longer life, smaller, more reliable, andhighly responsive PAP device. This provides a PAP device that is morecomfortable and easier to use for the patient. Because the patients aremore satisfied, therapy is easier to administer for the physician.

In addition, the PAP device 60 including the motor arrangement of FIG. 1provides a potentially lower cost due to reduced parts count and lessmachining, a superior motor platform for implementing conventionalrolling element bearings, a motor platform to accommodate fluidbearings, a motor platform to accommodate fluid bearings and adouble-ended, impeller blower construction, and/or a motor platform toaccommodate fluid bearings and a double-ended, impeller blowerconstruction and integral volutes and/or blower housings.

3. Alternative Embodiment of Electric Motor

FIGS. 3-1 and 3-2 illustrate an electric motor or tube motor 210according to another embodiment of the present invention. The tube motor210 is substantially similar to the tube motor 10 described above, andalso illustrates the motor's ability to function as a motor without therequirement of a housing or endcap.

As illustrated, the motor 210 includes a rotatable shaft or rotor 214including a permanent magnet 216 provided thereto, a “magneticallytransparent” bearing tube 222 structured to retain or house bearings 220that rotatably support the rotor 214 within the tube 222, and a statorassembly 218 provided along an exterior surface of the tube 222 (e.g.,retained on tube by friction).

In the illustrated embodiment, the stator assembly 218 includes windings219, a stator or stator lamination stack 221 provided to the windings219, and one or more insulators 223 provided between the windings 219and the stack 221 to insulate the stack 221 from the windings 219. Asdescribed above, the tube 222 is “magnetically transparent”, whichallows the stator assembly 218 to act on the magnetic rotor 214positioned within the tube 222 without significant loss of flux densityand/or increased heat, if any.

A spacer 234 is provided between the rotor magnet 216 and one of thebearings 220, and a spring or biasing element 236 is provided betweenthe rotor magnet 216 and the other of the bearings 220. This arrangementmaintains alignment of the rotor magnet 216 with the stator assembly218.

In the “tube motor” described herein, the housing elements are replacedby a single tube 222 that extends through the core of the statorassembly 218. The tube 22 is thin-walled (but strong) and is“magnetically transparent”, which allows the bearings to be mountedwithin a single bore with the rotor magnet nested therebetween. Therotor's magnetic flux penetrates the wall of the tube (since the tube is“magnetically transparent”) to interact with stator winding currents toproduce shaft torque.

Thus, the “tube motor” is self-contained wherein the stator and rotorare supported and/or contained by the tube in a manner that allows thetube motor to function as a motor. That is, a housing or endcap is notneeded to support and/or contain the stator and/or rotor, e.g., housingnot needed to support motor bearings. In PAP devices, a housing and/orendcap may be provided to the tube motor to define a plenum chamber forpressurized gas.

3.1 Benefits and Features

Benefits and features of the tube motor 210 include one or more of thefollowing:

Low cost;

Housing-less: no requirement for housing or endcap;

High performance capable;

Low inertia;

Dual shaft capable;

Tube provides excellent bore-to-bore concentricity (low noise withoutneed for highly precise machined housing parts);

Facilitates vibration isolation;

High power efficiency (low iron loss);

Good thermal properties (especially for the stator), e.g., due to thecooling effect on the stator with pressurized gas directed around thestator. The reduced heat on the stator and bearings may increase thereliability and life of the motor. Also, heat may be passed to thepressurized gas to assist in warming the gas;

Compact construction;

Highly manufacturable;

Slotless stator (zero cogging);

Sensorless (or “sensored”—if necessary);

Sine drivable (e.g., about 1.1% THD (Total Harmonic Distortion)); and/or

Reduction or elimination in tolerances by using the tube (e.g., notolerance may be required for the stator from the rotor/statoralignment).

It should be appreciated that the motors 10, 210 may include one or moresimilar advantages, benefits and/or features.

4. Alternative Embodiment of PAP Device

FIGS. 4-1 to 4-3 illustrate a PAP device or blower 360 according toanother embodiment of the present invention. As illustrated, the PAPdevice 360 includes a volute or housing 362 that defines a generallyspiral-shaped channel 363, a tube motor 310 including a “magneticallytransparent” tube 322 support by or within the housing 362, an impeller368 provided to the rotor 314 of the tube motor 310, and a lid or endcap 365 provided to the housing 362 to enclose the impeller 368.

As best shown in FIG. 4-2, the PAP device 360 is operable to draw asupply of gas into the housing through an inlet 367 and provide apressurized flow of gas at an outlet 366. The PAP device 360 isgenerally cylindrical with the inlet 367 aligned with an axis of the PAPdevice and the outlet 366 structured to direct gas exiting the PAPdevice in a generally tangential direction.

In an embodiment, the PAP device 360 may have a diameter of about 60 mmand a height of about 30 mm, which provides a cylindrical volume ofabout 85 cm³. The outlet 366 may have a diameter of about 10 mm. It isto be understood that these dimensions are merely exemplary and otherdimensions are possible depending on application.

4.1 Tube Motor

The tube motor 310 includes a rotatable shaft or rotor 314 including apermanent magnet 316 provided thereto, a “magnetically transparent” tube322 structured to retain or house bearings 320, 325 that rotatablysupport the rotor 314 within the tube 322, and a stator assembly 318provided along an exterior surface of the tube 322 (e.g., retained ontube by friction).

The stator assembly includes windings 319, a stator or stator laminationstack 321 (e.g., slotless or toothless) provided to the windings 319,and one or more insulators 323 provided between the windings 319 and thestack 321 to insulate the stack 321 from the windings 319. Furtherdetails of coil winding is disclosed in U.S. Provisional Application No.60/877,373, filed Dec. 28, 2006, which is incorporated herein byreference in its entirety.

4.1.1 One-Piece Tube

The tube 322 of the tube motor 310 includes a tube portion 370, a shield372 provided to one end of the tube portion 370, and an annular flange374 extending from the shield 372. In the illustrated embodiment, thetube 322 is integrally molded (e.g., injection molded) as a one-piecestructure. However, the tube 322 may be constructed in other suitablemanners.

4.1.2 Bearing Alignment and Retention

The tube portion 370 of the tube 322 is structured to retain and alignthe bearings 320, 325 that rotatably support the rotor 314. In theillustrated embodiment, the tube portion 370 is structured such thatmixed bearing sizes may be used.

As illustrated, the upper end of the tube portion 370 is structured tosupport bearing 320 and the lower end of the tube portion 370 isstructured to support bearing 325 having a smaller size or diameter thanbearing 320.

Specifically, the upper end of the tube portion 370 includes an annularsurface 376 defining a diameter D and adapted to support bearing 320.The lower end of the tube portion 370 includes an annular surface 378defining a smaller diameter d and adapted to support bearing 325. Asillustrated, the one-piece tube portion 370 provides accuratebore-to-bore alignment which provides accurate bearing-to-bearingalignment. The upper end of the tube portion 370 also includes one ormore extensions 338 structured to strengthen the upper end of the tubeportion 370 supporting the bearing 320.

In an embodiment, the tube portion may be manufactured such thatsubstantially no draft angle is provided along surfaces 376, 378 adaptedto support respective bearings 320, 325. However, a draft angle may beprovided along the surface between surfaces 376 and 378 to facilitatemolding along the line of draw.

A sloped surface 377 may be provided between surfaces 376, 378 to guidethe rotor 314 (with bearings 320, 325 provided to respective endportions) into the lower end of the tube portion 370. For example, thesmaller bearing side of the rotor 314 may be inserted into or “droppedinto” the tube portion 370 through the upper end of the tube portion370. As the smaller bearing 325 approaches the lower end, the slopedsurface 377 will guide the bearing 325 into engagement with surface 378having a reduced diameter. Thus, the bearing 325 is self-guided into itsoperative position.

In the illustrated embodiment, the lower end of the tube portion 370includes a flange 380 that provides a stop or support for the bearing325 at the lower end. Also, the upper end of the tube portion 370includes one or more tapered flange portions 382 adapted to engage thebearing 320, and hence retain the rotor within the tube portion 370.

The tapered flange portions 382 provide snap-in bearing retention. Thatis, the tapered flange portions 382 may be resiliently deflected uponrotor assembly to allow the bearing 320 to snap into the tube portion370, but prevent removal of the bearing 320 (and hence the rotor) fromthe tube portion 370 once assembled.

A spring or biasing element 336 may be provided between the bearing 320and the rotor magnet 316 to maintain alignment of the rotor magnet 316with the stator assembly 318.

4.1.3 Shield

The shield 372 of the tube 322 forms an upper wall or cutoff for thechannel 363 that directs pressurized gas to the outlet 366. In theillustrated embodiment, the shield 372 is in the form of a circular diskthat is provided to (e.g., integrally formed in one-piece) an end of thetube portion 370 adjacent the impeller 368.

In the illustrated embodiment, the outer edge of the shield 372substantially aligns with or extends radially beyond the outer edge ofthe impeller 368. The shield 372 provides a narrow annular gap 385(e.g., about 1 mm) between its outer edge and the wall of the housing362, which is sufficient to direct gas into the channel 363 leading tothe outlet 366.

4.2 Tube Motor and Housing Engagement

The tube motor 310 and the housing 362 provide complementary structuralelements that are adapted to support, align, and/or contain the tubemotor 310 within the housing 362.

In the illustrated embodiment, the housing 362 includes one or moreslots 384 in an upper portion of the housing wall that is adapted toreceive respective tabs 386 provided along the outer edge of the shield372 (e.g., see FIG. 4-1). In an embodiment, the shield 372 includesthree tabs 386 that are received in respective slots 384 of the housing362. However, any suitable number of slots/tabs may be provided.

The housing 362 and tube 322 cooperate to support and maintain thestator assembly 318 in an operative position. As illustrated in FIGS.4-1 and 4-3, the annular flange 374 of the tube 322 is structured toenclose an upper portion of the windings 319 and engage an upper side ofthe stack 321. Similarly, the bottom wall of the housing 362 includes anannular flange 388 that is structured to enclose a lower portion of thewindings 319 and engage a lower side of the stack 321. Thus, the annularflanges 374, 388 cooperate to enclose and sandwich the stator assembly318 between the housing 362 and the tube 322.

Also, each flange 374, 388 includes one or more anchoring protrusions390 (also referred to as anchoring pips or locating pins) that areadapted to engage within corresponding holes 391 provided through thestack 321. This arrangement self-adheres and/or aligns the housing 362and the tube 322 to the stack 321. In the illustrated embodiment,exterior surfaces of the flanges 374, 388 are substantially flush withan exterior surface of the stack 321.

In addition, the bottom wall of the housing 362 includes an opening 392adapted to receive the lower end of the tube portion 370 of the tube322. One or more tabs 394 may be provided along the edge of the opening392 that are adapted to engage within respective openings 396 providedin the lower end of the tube portion 370.

In an embodiment, the above-described complementary structural elementsprovided to the tube motor 310 and the housing 362 may provide snap-fitretention.

4.3 Impeller

In the illustrated embodiment, the PAP device 360 includes a singleimpeller 368. As illustrated, the impeller 368 includes a plurality ofcontinuously curved or straight blades 369 sandwiched between a pair ofdisk-like shrouds 371, 373. The smaller shroud 373 incorporates the hubor bushing 375 that is adapted to receive an end portion of the rotor314. Further details of impellers are disclosed in PCT Application No.PCT/AU2006/001617, filed Oct. 27, 2006, which is incorporated herein byreference in its entirety.

This arrangement provides a low cost and low inertia alternating shroudimpeller. In an embodiment, a gap G (e.g., see FIG. 4-3) may becontrolled by a press-to-shim technique. For example, a shim 333 may beprovided along the upper end of the tube 322 that is adapted to engagethe lower end of the hub 375 of the impeller 368 (as the hub 375 ismounted to the rotor 314) and hence control the size of the gap G.

In an embodiment, the impeller 368 may have a diameter of about 50 mm.It is to be understood that this dimension is merely exemplary and otherdimensions are possible depending on application.

4.4 Optional Balance Ring

As shown in FIG. 4-1, a balance ring 398 may be optionally provided toan opposite end portion of the rotor 314 (opposite the end portionsupporting the impeller 368).

This arrangement may facilitate single-plane or two-plane balancing ofthe tube motor 310.

4.5 Fluid Flow Path

As best shown in FIG. 4-3, gas enters the PAP device at the inlet 367and passes into the impeller 368 where it is accelerated tangentiallyand directed radially outward. The gap 385 between the outer edge of theshield 372 and the wall of the housing 362 allows gas to pass into thechannel 363 and down around the sides of the tube motor 310. Gas passesaround the channel 363 and the sides of the tube motor 310 flowing in aspiral manner with towards the outlet 366.

4.5.1 Stator Cooling

In the illustrated embodiment, the exterior surface of the stack 321 ofthe stator assembly 318 is exposed to the channel 363 of the housing 362and hence is exposed to the gas passing through the channel 363. Thisarrangement allows forced-convection cooling of the stack 321 as gasflows through the channel 363 in use.

4.6 Simple Construction and Low Cost

The PAP device 360 includes a relatively basic construction with asingle impeller to provide relatively basic CPAP and/or SnorePAPtreatment.

In addition, the PAP device 360 provides four plastic molded (e.g.,injection-molded) parts, i.e., the housing 362, the tube 322, theimpeller 368, and the end cap 365. These molded parts (along with therotor 314, stator assembly 318, bearings 320, 325, and spring 336)provide an arrangement with relatively low component and assembly costs.

5. PAP Device with Flexible Core

FIGS. 5-1 to 5-6 illustrate a PAP device or blower 460 (e.g., to provideCPAP through BiLevel NIV treatment) according to another embodiment ofthe present invention. In this embodiment, the PAP device 460 includes ahousing 462 and a core 461 supported within the housing 462 by avibration isolation system 455. As described in greater detail below,the vibration isolation system 455 supports the core 461 in a flexible,vibration-isolated manner with respect to the housing 462 so that thecore 461 is substantially isolated from the housing 463. Thus,vibrations and/or other movement generated by the core 461 in use aresubstantially isolated from the housing 462.

5.1 Core

In the illustrated embodiment, the core 461 includes a tube motor 410including a “magnetically transparent” tube 422, a core housing 450structured to substantially enclose the tube motor 410, an impeller 468provided to one end portion of the rotor 414 of the tube motor 410, anda balance ring 498 provided to an opposite end portion of the rotor 414.

5.1.1 Tube Motor

As described above, the tube motor 410 includes a rotatable shaft orrotor 414 including a permanent magnet 416 provided thereto, a“magnetically transparent” tube 422 structured to retain or housebearings 420 that rotatably support the rotor 414 within the tube 422,and a stator assembly 418 provided along an exterior surface of the tube422 (e.g., retained on tube by friction).

The stator assembly 418 includes windings 419, a stator or statorlamination stack 421 (e.g., slotless or toothless) provided to thewindings 419, and one or more insulators 423 provided between thewindings 419 and the stack 421 to insulate the stack 421 from thewindings 419.

A spring or biasing element 436 may be provided between one of thebearings 420 and the rotor magnet 416 to maintain alignment of the rotormagnet 416 with the stator assembly 418.

5.1.2 Core Housing

In the illustrated embodiment, the core housing 450 includes a firsthousing part 452 provided to one end of the tube 422 and a secondhousing part 454 provided to the opposite end of the tube 422.

As illustrated, the first housing part 452 includes a shield 472 thatforms an upper wall or cutoff for the housing channel 463. An innerannular flange 474 and an outer annular flange 479 extend from theshield 472. In the illustrated embodiment, the shield 472 and impeller468 have a tapered or sloped configuration along its radial length.However, other suitable configurations of the shield and impeller arepossible.

As described above, the shield 472 provides a narrow annular gap 485between its outer edge and the housing 462, which is sufficient todirect gas into the housing channel 463.

The shield 472 includes an opening that allows one end portion of therotor 414 to pass therethrough. The edge of the opening includes anannular slot 484 that is adapted to receive one end of the tube 422.

Also, the inner annular flange 474 is structured to enclose an upperportion of the windings 419 and engage an upper side of the stack 421.The inner annular flange 474 includes one or more anchoring protrusions490 that are adapted to engage within corresponding holes 491 providedthrough the stack 421.

The second housing part 454 includes a main wall 487 and an annularflange 488 extending from the main wall 487. The main wall 487 includesan opening that allows the opposite end portion of the rotor 414 to passtherethrough. The edge of the opening includes an annular slot 489 thatis adapted to receive the opposite end of the tube 422.

Also, the annular flange 488 is structured to enclose a lower portion ofthe windings 419 and engage a lower side of the stack 421. The annularflange 488 includes one or more anchoring protrusions 493 that areadapted to engage within corresponding holes 491 provided through thestack 421.

Thus, the flanges 474, 488 cooperate to enclose and sandwich the statorassembly 418. In the illustrated embodiment, exterior surfaces of theflanges 474, 488 are substantially flush with an exterior surface of thestack 421, i.e., exterior surface of stack exposed. As described above,this arrangement allows forced-convection cooling of the stack 421 asgas flows through the housing channel 463 in use.

The core housing 450 also includes a cap 495 provided to the secondhousing part 454 and adapted to enclose the balance ring 498 at one endportion of the rotor 414.

In an alternative embodiment, one or portions of the core housing 450may be integrally formed in one piece with the tube 422, e.g., similarto tube 322 described above.

5.2 Housing

The housing 462 includes a main body 481 that provides an outer wall forthe housing channel 463 and a lid or end cap 465 provided to the mainbody 481 to enclose the core 461.

As best shown in FIGS. 5-1 and 5-4, the PAP device 460 is operable todraw a supply of gas into the housing through an inlet 467 and provide apressurized flow of gas at an outlet 466. The PAP device 460 isgenerally cylindrical with the inlet 467 aligned with an axis of the PAPdevice and the outlet 466 structured to direct gas exiting the PAPdevice in a generally tangential direction.

5.3 Vibration Isolation System

The vibration isolation system 455 includes a front suspension 456 (orfront vibration isolator) to support a front portion of the core 461 anda rear suspension 458 (or rear vibration isolator) to support a rearportion of the core 461. The front and rear suspension 456, 458 togethersupport the core 461 in a flexible, vibration-isolated manner withrespect to the housing 462.

5.3.1 Front Suspension

The front suspension 456 includes a plurality of biasing elements 457,e.g., flat springs. As best shown in FIG. 5-3, each biasing element 457includes one end portion 457(1) provided to the outer annular flange 479of the shield 472 of the core 461, an opposite end portion 457(2)provided to the main body 481 of the housing 462, and an intermediateportion 457(3) that provides a flexible structure to isolate the core461 from the housing 462.

In the illustrated embodiment, the one end portion 457(1) includes abent configuration adapted to receive the free end of the flange 479.The opposite end portion 457(2) includes a bent configuration adapted toengage within a slot 483 provided to the main body 481. The intermediateportion 457(3) is bent into a concertina or bellow-like configuration toprovide a flexible structure.

In use, the biasing elements 457 support the front portion of the core461 within the housing 462 while isolating the core 461 from the housing462, e.g., vibration isolated.

In addition, wire W from the windings 419 may be coupled to one or moreof the biasing elements 457, e.g., wire W connected to the end portion457(1). This allows the biasing elements 457 (e.g., flat springs formedof metal) to conduct current from an external source to the windings419. For example, FIGS. 5-1 and 5-2 illustrate external source S thatmay be coupled to end portion 457(2) to conduct current through thebiasing element 457 and to wire W from windings 419.

5.3.2 Rear Suspension

The rear suspension 458 is in the form of a resiliently flexible nipple459 (e.g., formed of a silicone material) having one end 459(1) providedto the cap 495 of the core housing 450 and an opposite end 459(2)provided to the main body 481 of the housing 462.

In the illustrated embodiment, the end 459(2) includes an annular recess497 adapted to receive the edge of an opening 499 provided in the lowerwall of the main body 481.

In use, the resiliently flexible nipple 459 support the rear portion ofthe core 461 within the housing 462 while isolating the core 461 fromthe housing 462, e.g., vibration isolated.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of Any given assembly may constitute an additional embodiment.Furthermore, each individual component of any given assembly, one ormore portions of an individual component of any given assembly, andvarious combinations of components from one or more embodiments mayinclude one or more ornamental design features. In addition, while theinvention has particular application to patients who suffer from OSA, itis to be appreciated that patients who suffer from other illnesses(e.g., congestive heart failure, diabetes, morbid obesity, stroke,barriatric surgery, etc.) can derive benefit from the above teachings.Moreover, the above teachings have applicability with patients andnon-patients alike in non-medical applications.

1-65. (canceled)
 66. A PAP device for generating a supply of pressurizedgas to be provided to a patient for treatment, the PAP devicecomprising: a housing; a core including a motor and at least oneimpeller; and a vibration isolation system to support the core withinthe housing in a flexible, vibration-isolated manner.
 67. The PAP deviceaccording to claim 66, wherein the vibration isolation system includes afront suspension to support a front portion of the core and a rearsuspension to support a rear portion of the core.
 68. The PAP deviceaccording to claim 67, wherein the front suspension includes a pluralityof biasing elements.
 69. The PAP device according to claim 68, whereineach biasing element is in the form of a flat spring.
 70. The PAP deviceaccording to claim 68, wherein the biasing elements are structured tosupport the front portion of the core within the housing while isolatingthe core from the housing.
 71. The PAP device according to claim 68,wherein one or more of the biasing elements are coupled to windings of astator assembly to conduct current from an external source to thewindings.
 72. The PAP device according to claim 67, wherein the rearsuspension is in the form of a resiliently flexible nipple.
 73. The PAPdevice according to claim 72, wherein the nipple is formed of a siliconematerial.
 74. The PAP device according to claim 72, wherein the nippleis structured to support the rear portion of the core within the housingwhile isolating the core from the housing.
 75. A PAP device forgenerating a supply of pressurized gas to be provided to a patient fortreatment, the PAP device comprising: a housing; a core including amotor and at least one impeller; and a vibration isolation system tosupport the core within the housing in a flexible, vibration-isolatedmanner, wherein the vibration isolation system is adapted to be coupledto windings of a stator assembly to conduct current from an externalsource to the windings.
 76. A brushless DC motor, comprising: a rotor; astator assembly surrounding the rotor and adapted to control movement ofthe rotor; a support structure to support the rotor and the statorassembly in an operative position; and a vibration isolation systemprovided to the support structure and adapted to support the supportstructure within a housing in a flexible, vibration-isolated manner. 77.The motor according to claim 76, wherein the support structure includesa tube.
 78. The motor according to claim 76, wherein the vibrationisolation system is coupled to windings of the stator assembly toconduct current from an external source to the windings. 79-85.(canceled)